"Nothing compares to Celtic playing Rangers, absolutely nothing," Celtic legend and former Barcelona striker Henrik Larsson said about The Old Firm Derby in 2009, according to the Scottish Sun.

"'You can talk about Barca against their old rivals from Madrid, but, believe me, it's not even close. I've played in two of those matches, so I know what I am talking about.

"There is nothing bigger than the Glasgow derby."

Sectarianism has stoked the derby

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Rangers was founded in 1872 by a group of four young men who had met while playing football at Glasgow's West End Park.

15 years later, Celtic was founded by Irishman Brother Walfrid with the purpose of raising money to alleviate poverty in the immigrant Irish population in Glasgow's east end.

The local rivalry started as a friendly one, however the rise in religious and political tensions in the city during the 1920s and 1930s took its toll.

An influx of Irish Catholics into the east end of the city had led to increased competition for employment and housing, according to Nil By Mouth, to which the protestant population did not take kindly.

The divide pushed Catholics, and Celtic, closer to their Irish origins, while Rangers and its fans became more synonymous with Presbyterianism, according to FourFourTwo. Up until 1989, the latter did not sign a single Catholic player.

Celtic's Catholic fan base tends to advocate for Irish Republicanism, and the return of Northern Ireland to Irish ownership, while Rangers fans wish it remain a part of the UK.

The religious divide still exists today

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A study in 2006 by the Glasgow City Council showed that approximately 76% of Celtic fans identified as Catholic, whilst 65% of Rangers fans considered themselves Protestant.

The report also stated its belief that religious sectarianism was "still prevalent in Glasgow."

During the derby, Celtic fans can often be heard signing eulogies to Irish Republicans such as "The Boys Of The Old Brigade" whilst Rangers fans regularly belt out "The Sash" and other anthems espousing loyalty to the United Kingdom.

It leads to an tense and often hostile environment

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After Celtic beat Rangers in the 1980 Scottish Cup final at Hampden Park, Scotland's national stadium, hundreds of opposing fans flocked the pitch and engaged in an alcohol-fueled fight with bricks, pipes, and bottles that led to over 200 arrests.

The riot resulted in the Scottish Football Association banning alcohol from all matches.

However similar incidents continued to occur in the following years.

Bleacher Report says that between 1996 to 2003, at least eight deaths were directly linked to matches between Celtic and Rangers, as well as thousands of assaults and arrests.

Things aren't exactly tame on the pitch either

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Players are often known to become involved in the religious spat too, such as Paul Gascoigne, who played for Rangers in the mid 90s.

In January of 1998 , the Englishman infamously mimicked the playing of a flute — an offensive gesture against Irish Catholics — towards Celtic fans.

Not only was he fined for the action, but was also reportedly called and threatened by members of the Irish Republican Army (IRA), says The Belfast Telegraph.

He left Rangers for English side Middlesbrough two months later.

The Scottish title rarely leaves Glasgow

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Religious difference aside, the football in Glasgow is of course an integral part of The Old Firm, mostly because when the two sides do meet, they are almost always battling for the title.

Of the 122 championships available since the inception of the Scottish Football League (now the Scottish Premiership), the two sides have shared 104 — Celtic 50 and Rangers 54.

The last time a team from outside Glasgow won the Scottish title came in 1985, when Aberdeen beat Celtic to the trophy.

Though Rangers lead the race, it is The Hoops who have dominated in recent years, winning eight back-to-back titles.

Had it not been for the season being halted due the coronavirus pandemic, that tally would be nine, with Neil Lennon's side leading the table by 13 points with only eight games to go.